1. Field of the Invention
The present invention relates to a device and method for controlling heating power for cooking providing convenient and safe cooking and, more particularly, to a cooking apparatus which automatically evaluates the quantity and content of cooking material containing moisture and controls the heat amount applied to the cooking material.
2. Description of the Prior Art
In FIGS. 13 and 14, a conventional gas cooking range is described below. As shown in FIG. 13, an example of conventional cooking apparatus Rc includes a control panel 101, a burner 102, a grate 103, a burner control knob 104, a pan bottom temperature sensor 105 for detecting a temperature at a bottom of a pan (not shown), and an ignition/shut-off button 106.
The control panel 101 has a plurality of cooking mode keys which are prepared for performing predetermined and preferable cooking procedures for the desirable cooking materials. For example, a boil key is operated to heat the contents within the pan until it boils and automatically turns the burner off once the contents boils, and a simmer key is to operated to heat the contents of the pan until it boils and then automatically lowers the burner to a lower heat setting and activates the shut-off timer to cause the contents to simmer for the preset time. To cook using the automatic control feature of the cooking range Rc, a user selects any of cooking mode keys and presses the ignition/shut-off button 106 to start the burner 102.
In FIG. 14, the heating operation of the conventional gas range Rc when the simmer mode is performed is shown. The temperature rise da per unit time dt is calculated from the time when the pan bottom sensor 105 detects a temperature of 78.degree. C. to monitor the magnitude of the increase in the temperature gain da and thereby determine the quantity of water in the pan. The estimated boiling point KA is determined according to the temperature rise da. After the estimated boiling point KA is reached, the boiling point fp is detected by comparing the temperature rise da1, da2 and so on per unit time to the expected increase in temperature for each water volume to determine when the water boils. Since it is considered that the water in the pan is boiling when the boiling point fp is detected, the caloric output of the burner 102 is then reduced to a constant level to cook the contents of the pan.
By maintaining the burner 102 at a constant caloric output, however, the total caloric output tends to be either too much or not enough depending upon the quantity and type of foods being cooked, and this control feature is therefore not really practical for everyday use. Thus, it is not practical to apply only one kind of constant caloric output after reaching the boiling point fp to the various kinds of cooking materials because the quantity and type of cooking materials also vary at cooking time.
Furthermore, in the conventional gas range Rc, a temperature 13.degree. C. above the boiling point fp is defined as a burning prevention point fg at which temperature the cooking material will burn. When the detected pan bottom temperature reaches the burning prevention point fg, the burner 102 is automatically turned off to prevent the cooking material from burning by an automatic over-heating suppression (burning prevention) device incorporated in the conventional gas cooking range Rc. Depending upon the heat conductivity of the pan as determined by the type and thickness of material used in the pan, and the contents of cooking material in the pan, specifically how much moisture is included in the cooking material, using a constant temperature rise of 13.degree. C. from the boiling point fp to determine the burning prevention point fg tends to result in burnt foods when the moisture content is low. On the other hand, if the burning prevention point fg is set at much below a temperature 13.degree. C. above the boiling point fp, the automatic over-heating suppressing device functions before the contents are fully cooked. It is therefore not practically possible to set the threshold temperature for the over-heating suppression function at less than a 13.degree. C. rise from the boiling point fp.
Controlling the over-heating suppression function at a single temperature as a burning point makes it difficult to maintain a consistent level of doneness due to the heat conductivity of the pan as determined by the type and thickness of the material used in the pan and the amount of moisture in the pan.